1. Field of the Invention
The present invention relates to a slide fastener in which a stopper portion is molded on a slide fastener tape by melting a resin stopper material having a U-shaped section with a pressure by ultrasonic heating, high-frequency heating or heating with a heater adjacent to fastener elements attached on a side edge of the fastener tape.
2. Description of the Related Art
Conventionally, as an upper stopper provided by melting resin material, generally, a film-like or monofilament-like material is attached on a top face of the fastener tape or fastener elements by welding means. For example in case of an upper stopper of a slide fastener disclosed in Japanese Patent Application Publication No. 48-37421, for example, monofilament made of thermoplastic synthetic resin such as polyester resin, or polyamide resin is cut out to a predetermined length and bent into a U shape and attached to an inverted portion or a leg portion of a coil-like fastener element by welding and pressing under a pressure. In case of an upper stopper of a slide fastener disclosed in Japanese Patent Application Publication No. 49-36975, a coil-like fastener element about as large as a bead formed on the side edge of a fastener tape is attached to the bead and then, a short filament material is placed on this fastener element, the bead and the top face of part of the fastener tape and these parts are melted and then solidified so as to mold the stopper portion.
However, because the upper stopper portions of these known slide fasteners are molded on only the top face of the fastener tape by welding, their mounting strength on the fastener tape is weak and the stopper portion which receives the largest impact when a slider flange strikes it is separated easily from the fastener tape, so that they do not endure a long-term usage. The top face of the slide fastener and its constituent members in this specification refers to an outside face of a product on which this slide fastener is mounted and its bottom face refers to its inside surface.
To aim at solving such a problem, conventionally, for example, Japanese Utility Model Application Laid-Open No. 62-148116 and Japanese Utility Model Application Publication No. 5-31932 have disclosed slide fasteners having the synthetic resin upper stopper which is never separated and ensures a large melting strength. According to these publications, those upper stoppers sandwich upper and lower faces of the side edge of a fastener tape and ends of the upper stopper on both the upper and lower surfaces on the tape main body are connected like a bridge through a gap or an opening between composition yarns of a woven or knit fabric so that they are welded integrally.
In any upper stopper molded in a flat ring shape of the slide fastener disclosed in the above respective publications, its surface is formed in a smooth flat plane. Thus, a contact area with an inner face of a slider is large and at the time of starting sliding of the slider so as to open the slide fastener, its sliding resistance is large so that a user cannot help feeling a heaviness. Further, not only the aforementioned flat shape of the upper stopper just increases the sliding resistance of the slider but also depends largely upon a separation resistance against biting of slider when slider's sliding is started.
Generally, closing of the slide fastener by sliding operation of the slider is attained by a contact between opposing end faces of right and left upper stoppers and the connecting post portion of the slider, and also by a contact between an end portion on the side of the tape main body of the upper stopper and the front face of the flange portion. Because when the upper stopper makes a contact with the slider, a quite large striking force is applied to the upper stopper due to the sliding operation of the slider, the slider may partially bite into the upper stopper. For the reason, the above-described fault occurs.
Generally, when the slide fastener is mounted on clothes, the bottom face of the same fastener is directed to the human body side and depending on a case, makes a direct contact with the skin. Thus, if such a minute protrusion is expanded from the bottom face of the fastener tape, it provides the skin with prickly feeling because it is a minute upper stopper. Further, when the slider is started, the upper stopper of the slide fastener is gripped with fingers of one hand while the pull tag is gripped with fingers of the other hand and operated. At this time, some people may feel disharmony because a hardness feeling of the upper stopper is transmitted to the fingers.
The prickly feeling and hardness feeling originate from a fact that the upper stopper is protruded outward from the surface of the fastener tape main body. From the above-mentioned patent publications 1 to 4, it is understood that any upper stopper is expanded outward from the surface of the fastener tape main body.
This invention has been achieved to solve these conventional problems and a specific object of the invention is to provide a slide fastener having a configuration which reduces a sliding resistance upon starting of its slider, originating from an upper stopper of the slide fastener, particularly an upper stopper formed by welding a U-shaped material of synthetic resin monofilament with heat under pressure and at the same time, eliminates prickly feeling and a feeling of disharmony originating from the shape of the upper stopper.